The path I have taken has been to attempt to follow the methods of many others. Yahoo has several groups which concern themselves with astrophotography the subscribing to these is a great resource. Most books on astronomy devote at least a chapter on this topic, methods and guidelines described are helpful.
The most motivating materials I have found are at the web sites of other amateur astronomers. I discovered very early, that Hap Griffin was able to produce images beyond belief with equipment not beyond reach. Some astrophotographers use cameras priced >$10k and scopes on mounts in similar ranges. I liked knowing that there was a real possibility of remarkable success and that it was only a matter of time and skill. It is always interesting to put theory into practice.
- Detailed Field of view and Scope Control
I will have aligned my mount to the night sky and Starry Night will direct my scope to point to whatever object I point and click on. Usually the target will be in the field of view and only minor adjustments will be needed to get the final framing.
Using the AstroPlanner package above and StarryNight, I can move from object to object even though in several cases I can not even see them. Often, objects are not bright enough to see but they can still be photographed.
Once the object is framed then the photography can start.
- Auto Guiding
The program K3CCDTools is used to make the auto guiding happen. I use a small CCD imaging camera connected to the PC through USB to monitor the reference star, the program automatically detects the drift of the reference star and provides equal and opposite correction commands to the mount. This prepares the mount and thus the main scope and camera for it's long multi minute exposures.
- Finally we get to take a picture
- OK, so now can take our real exposures.
Long exposure times are needed because of the low surface brightness of the object being taken. Clusters, which are comprised of hundreds of thousands of stars in a tight formation, usually always circular do not need long exposures. Large galaxies who's light energy is spread out need longer exposures. Nebulas who's light is int the red end of the spectrum where any consumer camera like the 10D do not have good sensitivity will need extended exposures. Usually the answer is as long as you can tolerate is the best. Increasing the ISO is not usually a good idea as a increase in noise will result. Imageplus, the same program used for focusing is used to execute all of the long bulb exposures, images are stored to the laptop.
Sit and wait, enjoy some coffee from home, in the quiet are what is needed now.
Remember the auto-guiding that was started needs to run the entire time...
Occasionally I have to keep in mind that with a German equatorial mount may become limited as it can not track past the meridian.
- Post Processing
Postprocessing starts with looking at each of the individual exposures.
Exposures with flaws like, someone kicked the tripod and made the exposure wonky are marked for discard. Ones with flashing airplanes streaking thought the frame are gently put into the trash. (these are all good reasons for multiple exposures) Below are two samples.
Once all of the frames are processed into one image the final result is achieved. In some cases it is like gold and others are clearly in need of another try. The top image pair, unprocessed above and result below are of Messier Object M42.
The Orion Nebula Messier 42 (M42, NGC 1976) is the brightest starforming, and the brightest diffuse nebula in the sky, and also one of the brightest deepsky objects at all. Shining with the brightness of a star of 4th magnitude, it visible to the naked eye under moderately good conditions, and rewarding in telescopes of every size, from the smallest glasses to the greatest Earth-bound observatories as well as outer-space observatories like the Hubble Space Telescope. It is also a big object in the sky, extending to over 1 degree in diameter, thus covering more than four times the area of the Full Moon.
The lower pair are of Messier Object 51. M51 was one of Charles Messier's original discoveries: He discovered it on October 13, 1773, when observing a comet, and described it as a "very faint nebula, without stars" which is difficult to see. M51 is the dominating member of a small group of galaxies, which also contains M63 and a number of fainter galaxies. As it is about 37 million light years distant and so conspicuous, it is actually a big and luminous galaxy. For the amateur, M51 is easy and a showpiece if the sky is dark, but is quite sensitive for light pollution which easily makes it fade in the background. Under very good conditions, even suggestions of its spiral arms can be glanced with telescopes starting from 4-inch. Low magnification is best for viewing this pair. This object is 1/6 of a degree across or about 2mm at arms length,... very small.
These two examples are near the extremes of what I can photograph. From the large and bright to the very small and faint. One thing is constant, the methods are the same, so this is how it is done, or at least this is the way I do it.